Definition: In this task, you are given an input list A comprising of numbers and alphabets. You need to extract and sort the unique alphabets in the list. The alphabets in the input list will only be in lowercase. Return -1 if there is no alphabet in the input list.
Input: ['f', 'u', '3859', '5717', 'n', 'o', '4275', 'p', 'p']

f, n, o, p, u